Re: [PATCH v1 07/11] x86: perf: intel_pt: Intel PT PMU driver

Peter Zijlstra
2014-02-17T14:46:30Z

On Thu, Feb 06, 2014 at 12:50:30PM +0200, Alexander Shishkin wrote:
> Add support for Intel Processor Trace (PT) to kernel's perf/itrace events.
> PT is an extension of Intel Architecture that collects information about
> software execuction such as control flow, execution modes and timings and
> formats it into highly compressed binary packets. Even being compressed,
> these packets are generated at hundreds of megabytes per second per core,
> which makes it impractical to decode them on the fly in the kernel. Thus,
> buffers containing this binary stream are zero-copy mapped to the debug
> tools in userspace for subsequent decoding and analysis.
>
> Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
> ---
> arch/x86/include/uapi/asm/msr-index.h | 18 +
> arch/x86/kernel/cpu/Makefile | 1 +
> arch/x86/kernel/cpu/intel_pt.h | 127 ++++
> arch/x86/kernel/cpu/perf_event.c | 4 +
> arch/x86/kernel/cpu/perf_event_intel.c | 10 +
> arch/x86/kernel/cpu/perf_event_intel_pt.c | 991 ++++++++++++++++++++++++++++++
> 6 files changed, 1151 insertions(+)
> create mode 100644 arch/x86/kernel/cpu/intel_pt.h
> create mode 100644 arch/x86/kernel/cpu/perf_event_intel_pt.c

Andi said that when itrace is enabled the LBR is wrecked; this patch
seems to fail to deal with that.